KR100637227B1 - Bi-directional scan driver and organic light emitting display device having the same - Google Patents

Abstract

A bidirectional scan driving device and an OLED(Organic Light Emitting Diode) display device having the same are provided to decrease a dead space by forming the bidirectional scan driving device without an additional control signal by applying an emission control signal output from the prior shift register to an input terminal of a shift register driving the next emission control signal line. A bidirectional scan driving device(121,122) connected with plural scan lines and emission control signal lines to output scan signals(S[1]~S[n]) and emission control signals(E[1]~E[n]) through the scan lines and emission control signal lines to a display unit(130) has plural shift registers(SR1~SRn). Each shift register shifts a starting signal(SP) applied to an input stage in synchronization with a clock signal(clk) in sequence and then outputs the shifted signal. The emission control signal output from the shift register driving the predetermined emission control signal line is applied to the input stage of the shift register driving the emission control signal line of the next stage.

Description

Bi-directional scan driver and organic light emitting display device having the same {Bi-directional scan driver and organic light emitting display device having the same}

1 is a schematic diagram illustrating a conventional organic electroluminescent display.

2 is a view showing a scanning line driving form of a conventional one-way scanning driving device.

3 is a view schematically showing a bidirectional scan driving device according to the present invention.

4 is a circuit diagram illustrating an example of a pixel circuit applied to the present invention.

5 is a diagram illustrating a driving waveform for driving the pixel circuit of FIG. 4.

6 is a block diagram illustrating a bidirectional scan driving device according to the present invention.

7 is a circuit diagram illustrating an embodiment of a bidirectional scan driving device according to the present invention.

Explanation of symbols on the main parts of the drawings

110: data driver 121: first scan driver

122: second scan driver 130: display unit

D [1] to D [m]: data signal

S [1] to S [n]: scan signal

E [1] to E [n]: light emission control signals

SR1 to SRn: shift register

The present invention relates to a bidirectional scan driving device and an organic light emitting display device having the same, and more particularly, to a bidirectional scan driving which can reduce a dead space by implementing a scan driving device in both directions without additionally required control signals. A device and an organic light emitting display device having the same.

1 schematically illustrates a conventional organic light emitting display device.

As shown in FIG. 1, the organic light emitting diode display includes a data driver 11, a scan driver 12, and a display 13 for displaying an image. The display unit 13 includes a plurality of data signal lines extending in the vertical direction and a plurality of scanning lines extending in the horizontal direction.

In the display unit 13 of the organic light emitting diode display, pixels 14 are defined in a matrix form by the data signal lines and the scan lines, and pixel circuits are formed in the pixels 14.

The data driver 11 transmits the data signals D [1] to D [m] to the display unit 13 through the data signal lines. The scan driver 12 applies the scan signals S [1] to S [n] through the scan lines to select the plurality of pixels 14 constituting the display unit 13 in line units. Information of the data signals D [1] to D [m] is transmitted to the pixels 14 selected by the scan signals S [1] to S [n]. Meanwhile, a predetermined voltage source supplies a constant power supply voltage Vdd to all the pixels 14 of the display unit 13 through a bus line.

2 is a diagram showing a scanning line driving mode of a conventional one-way scanning driving apparatus.

Referring to FIG. 2, the conventional scan driver 12 includes one or more shift registers SR1 to SRn, and the shift registers SR1 to SRn are connected to each of the one or more scan lines, and thus, through the scan line. The scan signal is output to the display unit 13. The shift register stores the input signal and outputs the stored data in response to a constant clock signal supplied by the system to be used. One or more shift registers SR1 to SRn included in the scan driver 12 are cascaded to each other so that the scan lines driven by the shift registers are sequentially selected in line units.

On the other hand, the controller 15 generates the start pulse SP, the clock signal clk and the inverted clock signal clkb supplied to the scan driver 12. In addition, each of the shift registers receives a start signal SP as an input terminal to perform a shift operation. In performing the shift operation, a clock signal clk and an inverted clock signal clkb applied from the controller 15 are executed. The start signal SP is shifted and outputted in synchronization with.

In particular, in the conventional case, the first shift register SR1 included in the scan driver 12 receives the start signal SP from the outside, and synchronizes the clock signal clk and the inverted clock signal clkb. The generated pulses were generated, and a scan signal and a light emission control signal required for driving the display unit 13 were generated using the generated pulses. On the other hand, by applying the pulse generated internally in the first shift register (SR1) to the input terminal of the next shift register (SR2), the second shift register (SR2) performs a shift operation by using the pulse as a start signal The scan signal and the emission control signal generated accordingly were outputted to the display unit 13.

However, when the scan driver is formed on one side of the display unit to drive the scan line in one direction as described above, the efficiency is reduced in terms of space arrangement due to the increase of dead space in the panel. In addition, when the scan drivers are formed on both sides of the display unit to drive in both directions, the addition of control signals for driving the scan drivers formed on both sides is required, resulting in an increase in the complexity of panel driving. do.

The technical problem to be achieved by the present invention is to reduce the dead space by implementing the scan drive device in both directions, bidirectional scan drive device that does not require additional control signal to implement the scan drive device in both directions And an organic light emitting display device.

The bidirectional scanning driving apparatus according to the present invention for achieving the above technical problem is connected to a plurality of scanning lines and light emission control signal lines, the scan drive for outputting the scan signal and the light emission control signal to the display unit through the scan line and the light emission control signal line, respectively. In the apparatus, the scan driving device includes a plurality of shift registers, each shift register sequentially shifts and outputs a start signal applied to an input terminal in synchronization with a predetermined clock signal, and drives a predetermined light emission control signal line. The light emission control signal output from the shift register is applied to the input terminal of the shift register for driving the light emission control signal line of the next stage.

Preferably, the scan driver includes a first scan driver located on one side of the display unit and including one or more shift registers and a second scan driver located on the other side of the display unit and including one or more shift registers. It is characterized by.

Further, the light emission control signal output from the shift register included in any one of the first scan driver and the second scan driver is applied to an input terminal of the shift register included in the other scan driver. It is desirable to.

Meanwhile, the organic light emitting diode display according to the present invention is connected to a display unit including a plurality of pixels, a plurality of scan lines and a light emission control signal line, and outputs a scan signal and a light emission control signal to a display unit through the scan line and the light emission control signal line, respectively. An organic light emitting display device comprising: a scan drive device; and a data drive device for causing the display to implement an image by controlling application of a data signal, wherein the scan drive device includes a plurality of shift registers, each shift register; Is a shift in which the start signal applied to the input terminal is sequentially shifted and output in synchronization with a predetermined clock signal, and the light emission control signal output from the shift register for driving the predetermined light emission control signal line drives the light emission control signal line for the next stage. It is characterized in that applied to the input of the register.

DETAILED DESCRIPTION In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

3 is a diagram schematically illustrating a bidirectional scan driver according to the present invention, and particularly, the bidirectional scan driver is provided in a flat panel display device to drive a scan line and a control signal line in both directions. In particular, the flat panel display may be an organic light emitting display device.

As illustrated in FIG. 3, the bidirectional scan driving device according to the present invention is connected to a plurality of scan lines and emission control signal lines, and scan signals S [1] into the display unit 130 through the scan lines and emission control signal lines. To S [n]) and the emission control signals E [1] to E [n]. In particular, the scan driver is provided with the first scan driver 121 and the second scan driver 122 positioned opposite to both sides of the display unit 130 so that the scan driver drives the scan line and the emission control signal line in both directions. Is preferably provided.

On the other hand, the data driver 110 transmits the data signals D [1] to D [m] to the display unit 130 through the data signal lines. The scan driver including the first scan driver 121 and the second scan driver 122 applies the scan signals S [1] to S [n] through the scan lines, thereby obtaining a plurality of pixels 140. Select by line. Information of the data signals D [1] to D [m] is transmitted to the pixels 140 selected by the scan signals S [1] to S [n]. Meanwhile, a predetermined voltage source supplies a constant power supply voltage Vdd to all the pixels 140 of the display unit 130 through a bus line.

The data signals D [1] to D [m] are transmitted in synchronization with the scan signals S [1] to S [n], whereby data is written to the pixel circuit provided in the pixel 140. In general, an organic light emitting diode display includes at least one capacitor element in a pixel circuit, and a predetermined voltage corresponding to the data signals D [1] to D [m] is stored in the capacitor element.

In this case, the emission control signals E [1] to E [n] may be applied to each pixel circuit in order to accurately write data in the pixel circuit or to control the emission period. Is performed by controlling a predetermined switching element to be turned on / off in response to the emission control signals E [1] to E [n], thereby controlling the application of a driving current to the organic light emitting element included in the pixel circuit.

Meanwhile, each of the first scan driver 121 and the second scan driver 122 constituting the scan driver includes one or more shift registers SR1 to SRn, and the shift registers SR1 to SRn are respectively. By cascading with each other, the scan lines driven by the respective shift registers SR1 to SRn are sequentially selected in line units.

In particular, the first scan driver 121 has an odd number of scan lines S [1], S [3], S [5], so that the scan driver drives the scan line and the light emission control signal line in both directions. ) And shift registers SR1, SR3, SR5 ... driving the emission control signal lines E [1], E [3], E [5] ..., and the second scan driver 122 ) Drives the even-numbered scanning lines S [2], S [4], S [6] ... and emission control signal lines E [2], E [4], E [6] ... The shift registers SR2, SR4, SR6... May be included. This is to allow the first scan driver 121 and the second scan driver 122 to alternately drive the scan line and the light emission control signal line sequentially. The above configuration is one example for implementing the bidirectional scan driving apparatus according to the present invention, and the first scan driving apparatus 121 drives the even-numbered scanning line and the emission control signal line and the second scanning driving apparatus 122 ) Can achieve the same purpose by driving the odd-numbered scanning line and the emission control signal line, and other applications can be achieved.

The first shift register SR1 of the first scan driver 121 receives the start signal SP from an external source as an input terminal, and has a predetermined clock signal clk and an inverted clock signal having a phase opposite to that of the clock signal. The start signal SP is shifted and output in synchronism with (clkb). As described above, a scan signal S [1] and a light emission control signal E [1] required for driving are generated from the shift-generated pulses and applied to the first scan line and the light emission control signal line.

Meanwhile, the first shift register SR2 of the second scan driver 122 receives a predetermined signal to an input terminal to drive the second scan line and the light emission control signal line. In this case, the first scan driver 121 is applied. The light emission control signal E [1] output by the first shift register SR1 is applied to the input terminal of the first shift register SR2 of the second scan driver 122. Accordingly, the emission control signal E [1] applied to the first shift register SR2 of the second scan driver 122 is shifted and output in synchronization with the clock signal clk and the inverted clock signal clkb. It is done. Further, the scan signal S [2] and the emission control signal E [2] are generated from the pulse generated by shifting as described above.

In the same manner as described above, the emission control signal E [2] generated from the first shift register SR2 of the second scan driver 122 is output to the display unit 130, and the emission control signal E [2] is applied to the input terminal of the second shift register SR3 of the first scan driver 121. The second shift register SR3 of the first scan driver 121 generates the scan signal S [3] and the emission control signal E [3] for driving the third scan line and the emission control signal line. do. The scanning operation is performed by sequentially repeating these operations.

In the case of the conventional scan driver, the bidirectional scan driver of the present invention is different from applying an internally generated pulse from one of the one or more shift registers cascaded to the input of the next shift register. The light emission control signal output from one of the shift registers is applied to the input of the next shift register. The above-described configuration is possible because the pulse generated internally in the shift register according to the present invention and the phase of the light emission control signal output to the display section are the same. Detailed description thereof will be described later.

Meanwhile, the emission control signals E [1] to E [n] are applied to the pixel circuits respectively employed in the pixels of the panel to control the driving current to the organic light emitting device. It demonstrates with reference.

FIG. 4 is a circuit diagram illustrating an example of a pixel circuit to which the light emission control signal is applied as described above, and the pixel circuit to be applied to the present invention is not limited thereto, and various types of pixel circuits may be applied. 5 is a diagram illustrating a driving waveform for driving the pixel circuit of FIG. 4.

The pixel circuit of FIG. 4 includes five transistors and two capacitor elements, wherein the first transistor M1 is a driving transistor, and the second to fifth transistors M2 to M5 operate as switching transistors. Preferably, the transistor comprises a field effect transistor (FET). In particular, in FIG. 4, the first to fourth transistors M1 to M4 include a P type field effect transistor, and the fifth transistor M5. Shows a case where N type field effect transistors are respectively applied.

The operation of the pixel circuit of FIG. 4 according to the driving waveform of FIG. 5 will be briefly described. The n-1 th scan signal S [n-1] and the light emission control signal E [n] during the T1 period are at a low level. By changing to, the second and fourth transistors M2 and M4 are turned on and the driving transistor M1 is diode-connected. In addition, since voltages of Vdd and Vdd + Vth are applied to both ends of the first capacitor Cvth, the voltage corresponding to Vth is stored in the first capacitor Cvth. In addition, the fifth transistor M5 is turned off during the T1 period to block the driving current from being applied to the organic light emitting diode OLED.

Thereafter, the n-1 th scan signal S [n-1] and the emission control signal E [n] are changed to the high level during the T2 period, and the n th scan signal S [n] is brought to the low level. By changing, the data signal D [m] is applied into the pixel circuit from the data signal line. Accordingly, the second capacitor Cst stores data according to the data signal D [m]. Also, as the voltage at one end of the first capacitor Cvth is changed from Vdd to Vdata, the voltage at the other end of the first capacitor Cvth connected to the main electrode of the driving transistor M1 is changed to Vdata + Vth. .

Accordingly, the voltage Vgs between the main electrode and the first electrode of the driving transistor M1 has a value of Vdata + Vth-Vdd, and the fifth transistor M5 is applied to the emission control signal E [ n]) is turned on to supply a driving current to the organic light emitting diode OLED. In this case, the driving current applied to the organic light emitting diode OLED has a value independent of the Vth value according to Equation 1 below, so that the luminance unevenness due to the threshold voltage deviation of the driving transistor M1 may be improved. It becomes possible.

는 유기 발광소자(OLED)에 흐르는 전류, Vgs는 제1 트랜지스터(M1)의 주전극과 제1전극 사이의 전압, Vth는 제1 트랜지스터(M1)의 문턱 전압, Vdd는 전원전압, Vdata는 데이터 전압, β는 이득 계수(gain factor)를 나타낸다.In Equation 1,

Is the current flowing through the OLED, Vgs is the voltage between the main electrode and the first electrode of the first transistor M1, Vth is the threshold voltage of the first transistor M1, Vdd is the power supply voltage, and Vdata is the data. The voltage β is a gain factor.

When the pixel circuit is designed to receive the emission control signal as described above, the scan driver outputs the scan signal and the emission control signal through the scan line and the emission control signal line, respectively. In this case, a detailed configuration of the scan driving device for realizing the scan line and the control signal line in both directions using the emission control signal will be described with reference to FIGS. 6 and 7.

6 is a block diagram illustrating a bidirectional scan driving device according to the present invention. As shown in FIG. 6, the bidirectional scan driver according to the present invention includes a first scan driver 121 and a second scan driver 122, and the first scan driver 121 and the second scan. The driver 122 includes one or more shift registers SR1 to SRn, respectively.

Each of the shift registers SR1 to SRn receives a predetermined start signal through an input terminal IN, and receives a first clock signal clk and a second clock signal clkb through a clock signal input terminal. The first clock signal clk and the second clock signal clkb have inverted phases. The predetermined start signal applied through the input terminal IN is shifted and output in synchronization with the first clock signal clk and the second clock signal clkb.

In addition, each of the shift registers SR1 to SRn applies a scan signal and a light emission control signal to a display unit (not shown) through the first output terminal and the second output terminal out1 and out2, respectively. The first output terminal and the second output terminal out1 and out2 are connected to the scan line and the emission control signal line, respectively.

As shown in FIG. 6, a start signal SP is applied to an input terminal IN of the first shift register SR1 of the first scan driver 121, and the start signal SP is a first clock. It is shifted and output in synchronization with the signal clk and the second clock signal clkb. The first scan signal S [1] and the emission control signal E [1] are generated to the display unit through these signals. Output In this case, a buffer including a NAND gate or one or more inverters may be included between the shift register, the scan line, and the emission control signal line. Accordingly, timing adjustment of an internally generated pulse signal is performed by shifting the start signal SP. Or buffer the signal.

The emission control signal E [1] output from the second output terminal out2 of the first shift register SR1 of the first scan driver 121 is the first shift of the second scan driver 122. It is applied to the input terminal IN of the register SR2, and is shifted and output in synchronization with the first clock signal clk and the second clock signal clkb. By repeating the above-described operation, the n scan lines and the light emission control signal lines can be driven in both directions. Also, in implementing the scan driver in both directions, no additional control signal is required to drive each scan driver.

7 is a circuit diagram showing in more detail an embodiment of a bidirectional scan drive device according to the present invention. The circuit diagram shown in FIG. 7 is only one example of implementing the bidirectional scan driver, and other scan drivers that perform the same or similar operation through simple changes of the elements and connection states of the circuit can be applied to the present invention. have.

Since the operation of the device provided in the bidirectional scan driver of FIG. 7 operates in the same or similar manner as the device provided in the conventional scan driver, a detailed description thereof will be omitted. As shown, the bidirectional scan drive device according to the present invention includes an OR gate and an inverter for shifting and outputting an input signal. The start signal applied to the input terminal of the first OR gate 201 is output in response to the predetermined clock signals clk1 and clk2 each having an inverted phase. In addition, the signal output from the first OR gate 201 is output as an inverted signal by the inverter 202. Further, a second OR gate 203 is further included, and the signal output from the inverter 202 is fed back to an input signal of the inverter 202 in response to a predetermined clock signal clk1 or clk2.

The input terminal of the shift register is connected to the first OR gate 201, and a start signal EM01 is applied to the input terminal of the first OR gate 201. The start signal EM01 is a light emission control signal output by the shift register driving the immediately preceding scan line and the light emission control signal line, and the shift register uses the light emission control signal EM01 output by the previous shift register as a start signal. The start signals are shifted and output by the OR gates 201 and 203 and the inverter 202.

The scan driving device may further include NAND gates 211 and 212, and the NAND gates 211 and 212 may include output terminals of the inverter 202 and shift registers for outputting scan signals S2 and S3 to scan lines. It is connected between the outputs. Signals output through the OR gates 201 and 203 and the inverter 202 and predetermined light emission control signals are applied to the input terminals of the NAND gates 211 and 212, and two signals applied to the input terminals are predetermined clock signals sclk0. is output by performing a NAND operation by (sclk1). The output signal passes through two inverters 223, 224 or 225, 226 to generate scan signals S2 and S3.

In addition, the emission control signal EM23 is generated by outputting a signal generated internally through the OR gates 201 and 203 and the inverter 202 through a buffer consisting of two inverters 221 and 222. Accordingly, the signal generated internally in the scan driver has the same phase as the emission control signal EM23. Therefore, unlike conventionally applying the signal generated inside the scan driver to the input stage of the next stage shift register, the emission control signal can be applied to the input stage of the next stage shift register to generate the pulse signal of the same phase. have.

On the other hand, the next shift register receives the light emission control signal EM23 as a start signal and shifts it by predetermined clock signals clk1 and clk2 to output it. The output internal signal is output through a buffer consisting of two inverters 251 and 252, thereby generating a light emission control signal EM45. Further, the emission control signal EM45 is applied to the input terminal of the next shift register. Meanwhile, the NAND gates 241 and 242 and the predetermined inverters 253 to 256, which are not described in the drawing, operate in the same manner as the NAND gates 211 and 212 and the predetermined inverters 223 to 226 described above. S5) is generated.

On the other hand, the organic light emitting diode display according to the present invention is characterized in that it comprises a bidirectional scanning driving device configured as described above. The organic light emitting diode display according to the present invention includes a display unit including a plurality of pixels, and a scan driver including a first scan driver and a second scan driver disposed on both sides of the display unit.

The scan driving device drives the scan line and the light emission control signal line in both directions as described above, and the light emission control signal output from the previous shift register is applied to the input terminal of the shift register for driving the next light emission control signal line. It is done.

As described above, optimal embodiments have been disclosed in the drawings and the specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the bidirectional scan driver and the organic light emitting diode display including the same according to the present invention can reduce dead space by implementing the scan driver in both directions without additional control signals. have.

Claims (6)

A scan driving device connected to a plurality of scan lines and a light emission control signal line and outputting a scan signal and a light emission control signal to a display unit through the scan line and the light emission control signal line, respectively. The scan driver includes a plurality of shift registers, each shift register sequentially shifts and outputs a start signal applied to an input terminal in synchronization with a predetermined clock signal, A light emission control signal output from a shift register for driving a predetermined light emission control signal line is applied to an input terminal of a shift register for driving a next light emission control signal line. The method of claim 1, The scan driving device may include a first scan driving device positioned on one side of the display unit and including one or more shift registers; And And a second scan driver positioned on the other side of the display unit and including one or more shift registers. The method of claim 2, The light emission control signal output from the shift register included in any one of the first scan driver and the second scan driver is applied to an input terminal of the shift register included in the other scan driver. A bidirectional scanning drive characterized in that. A display unit including a plurality of pixels; A scan driving device connected to a plurality of scan lines and light emission control signal lines to output scan signals and light emission control signals to a display unit through the scan lines and light emission control signal lines; An organic light emitting display device comprising: a data driver configured to control an application of a data signal so that the display unit implements an image. The scan driver includes a plurality of shift registers, each shift register sequentially shifts and outputs a start signal applied to an input terminal in synchronization with a predetermined clock signal, And a light emission control signal output from a shift register for driving a predetermined light emission control signal line is applied to an input terminal of a shift register for driving the next light emission control signal line. The method of claim 4, wherein The scan driving device may include a first scan driving device positioned on one side of the display unit and including one or more shift registers; And And a second scan driver positioned on the other side of the display unit and including one or more shift registers. The method of claim 5, The light emission control signal output from the shift register included in any one of the first scan driver and the second scan driver is applied to an input terminal of the shift register included in the other scan driver. Organic electroluminescent display.

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